Continuous Administration of Dopa Decarboxylase Inhibitors and Compositions for Same

ABSTRACT

Disclosed herein are compositions that include for example the arginine salt of carbidopa, and methods for treating neurological or movement diseases or disorders such as restless leg syndrome, Parkinson&#39;s disease, secondary parkinsonism, Huntington&#39;s disease, Parkinson&#39;s like syndrome, PSP, MSA, ALS, Shy-Drager syndrome and conditions resulting from brain injury including carbon monoxide or manganese intoxication, using substantially continuous administration of carbidopa or salt thereof together with administration of levodopa.

RELATED APPLICATION

This application is a continuation of U.S. Ser. No. 12/781,357, filedMay 17, 2010, which claims priority to U.S. Ser. No. 61/179,511, filedMay 19, 2009, all of which are hereby incorporated by reference in itsentirety.

BACKGROUND

Parkinson's disease is a degenerative condition characterized by reducedconcentration of the neurotransmitter dopamine in the brain. Levodopa(L-dopa or L-3,4-dihydroxyphenylalanine) is an immediate metabolicprecursor of dopamine that, unlike dopamine, is able to cross theblood-brain barrier, and is most commonly used for restoring thedopamine concentration in the brain. For the past 40 years, levodopa hasremained the most effective therapy for the treatment of Parkinson'sdisease.

However, levodopa has a short half life in plasma that, even under bestcommon current standard of care, results in pulsatile dopaminergicstimulation. Long-term therapy is therefore complicated by motorfluctuations and dyskinesia that can represent a source of significantdisability for some patients. A therapeutic strategy that couldultimately deliver levodopa/dopamine to the brain in a more continuousand physiologic manner would provide the benefits of standard levodopawith reduced motor complications and is much needed by patientssuffering from Parkinson's disease and other neurological or movementdisorders (Olanow C W; Mov. Dis. 2008, 23 (Suppl. 3):S613-S622).Sustained-release oral levodopa formulations have been developed, but,at best, such preparations have been found to be no more efficaciousthan standard tablets. Continuous administration of levodopa byintraduodenal administration or infusion has also been attempted byusing ambulatory pumps or patches. Such treatments, especiallyintraduodenal, are extremely invasive and inconvenient. Further, suchtreatments may be associated with dopaminergic adverse events;continuous administration of levodopa or dopa agonists is stillassociated with off periods that are self-limiting despite continueddelivery of the drug. Nutt J G; Mov. Dis. 2008, 23 (Suppl. 3):5580-4.

The metabolic transformation of levodopa to dopamine is catalyzed by thearomatic L-amino acid decarboxylase enzyme, a ubiquitous enzyme withparticularly high concentrations in the intestinal mucosa, liver, brainand brain capillaries. Due to the possibility of extracerebralmetabolism of levodopa, it is necessary to administer large doses oflevodopa leading to high extracerebral concentrations of dopamine thatcause nausea in some patients. Therefore, levodopa is usuallyadministered concurrently with oral administration of a dopadecarboxylase inhibitor, such as carbidopa or benserazide, which reducesby 60-80% the levodopa dose required for a clinical response, and thusprevents certain of its side effects by inhibiting the conversion oflevodopa to dopamine outside the brain. Exactly how this dose reductionis accomplished is uncertain. Various formulations comprising levodopaalone or together with inhibitors of enzymes associated with themetabolic degradation of levodopa are well known, for example,decarboxylase inhibitors such as carbidopa and benserazide,catechol-O-methyl transferase (COMT) inhibitors such as entacapone andtolcapone, and monoamone oxidase (MAO)-A or MAO-B inhibitors such asmoclobemide, rasagiline or selegiline or safinamide. Currently availableoral drugs include SINEMET® and SINEMET® CR sustained-release tabletsthat include carbidopa or levodopa; STALEVO® tablets containingcarbidopa, entacapone and levodopa; and MADOPAR® tablets containinglevodopa and benserazide. There is an on-going and urgent need formethods and compositions that can effect continuous stimulation ofL-dopa to more effectively treat movement disorders such as Parkinson'sdisease.

Carbidopa [(−)-L-α-hydrazino-α-methyl-β-(3,4-dihydroxybenzene) propanoicacid monohydrate], a white, crystalline compound, only slightly solublein water, is a dopa decarboxylase inhibitor commonly administered withlevodopa. Only 40-70% of an oral dose of carbidopa is absorbed in man,monkey and dog. Although carbidopa has been orally administered withlevodopa for over 30 years, no stable liquid formulation having e.g., aneffective concentration in a volume suitable for use for subcutaneous ortransdermal delivery has ever been achieved. There is an urgent, longstanding need for such carpidopa formulations that can be administeredmore easily to patients, especially as compared to current invasivemodes such as duodenal administration.

SUMMARY

This disclosure relates at least in part to the discovery that anarginine salt of carbidopa can form a stable, liquid formulation,suitable for e.g., continuous subcutaneous, transdermal, intradermal,intravenous and/or intraduodenal administration, at a physiologicallyacceptable pH. Such disclosed compositions are capable of substantiallycontinuously administering carbidopa to a patient in need thereof. Forexample, disclosed herein are compositions that relate to the discloseddiscovery that substantially continuously administering a dopadecarboxylase inhibitor such as carbidopa, together with discrete (e.g.oral) co-administration of levodopa, may stimulate L-dopa substantiallycontinuously and thus e.g., extend the effectiveness of a levodopa oraldosing regimen and/or reduce the daily dosage of levodopa, whileeffectively treating a movement and/or neurological disorder such asParkinson's disease.

In an embodiment, this disclosure provides for carbidopa and/or levodopasalts with a basic amino acid such as arginine. For example, thedisclosure provides for an arginine salt of levodopa or carbidopa thatis suitable for e.g., continuous subcutaneous, trandermal, intradermal,intravenous, oral, or intraduodenal administration.

Also contemplated herein are pharmaceutically acceptable liquid (e.g.,liquid at room temperature) or gel formulations or compositions thatinclude an arginine salt of carbidopa, e.g., include carbidopa andarginine, that may be suitable for substantially continuousadministration to a patient e.g. with or without use of, for example, atransdermal patch or subcutaneous pump (e.g. an insulin-like pump). Suchcontemplated liquid compositions may include at least 1%, at least 4%,at least 6% or more by weight carbidopa, (e.g. about 2% to about 6% byweight carbidopa) and therefore may facilitate administration of smalleramounts of a pharmacologically acceptable formulation to achieveefficacy as compared to a carbidopa formulation that is only capable ofhaving less than 1% by weight carbidopa. In another embodiment,contemplated herein is a liquid or gel composition that includes a molarratio of about 1.0:0.5 to about 1: to about 2.5, e.g., 1:1.0-1.2 molarratio of carbidopa:basic amino acid, e.g. carbidopa:arginine. A liquidcomposition that includes carbidopa and a basic amino acid, ascontemplated herein, may have a physiologically acceptable pH, e.g. a pHof about 6.5 to 9.5, e.g., about 7 to about 9, or about 8 to about 9, at25° C.

In yet another embodiment, contemplated herein is a pharmaceuticallyacceptable liquid or gel composition that includes a molar ratio ofabout 1.0:0.5 to about 1:2, e.g., about 1:1.8 molar ratio oflevodopa:arginine. For example, provided herein is a liquid compositionthat may include at least about 4% by weight, or at least 5%, at leastabout 6% (e.g. about 3% to about 7%) or more by weight levodopa. Aliquid composition having levodopa and a basic amino acid, ascontemplated herein, may have a pH of about 8 to 10, e.g., about 8.5 toabout 9.5, at 25° C.

Exemplary liquid compositions contemplated herein may be liquidsolutions, e.g. may be a substantially homogenous mixture that includescarbidopa and arginine, and may include water, or alternatively may besubstantially non-aqueous. In other embodiments, contemplatedcompositions may also include other active agents such as entacaponeand/or tolcapone and/or may include one or more pharmaceuticallyacceptable excipients such as N-methylpyrrolidone (NMP),polyvinylpyrrolidone (PVP), propylene glycol, antioxidants, orcombinations thereof.

In some embodiments, disclosed compositions, e.g. liquid compositions,may be substantially stable at 25° C. for at least about 48 hours ormore.

In one aspect, provided herein is a kit comprising a first formulationsuitable for continuous administration to a patient comprising anarginine:carbidopa salt and a second formulation suitable for e.g. oraladministration comprising levodopa or an arginine salt of levodopa andoptionally instructions for use.

Also provided herein, in one embodiment, is a method for treatment of adisease or disorder characterized by reduced levels of dopamine in apatient's brain, (e.g. Parkinson's disease), comprising substantiallycontinuously administering to a patient in need thereof atherapeutically effective amount of a decarboxylase inhibitor, a salt oran ester thereof, and administering a therapeutically effective amountof levodopa or pharmaceutically acceptable salt thereof (e.g., argininelevodopa), or composition comprising levodopa (for example,administering a composition e.g. a tablet, having levodopa as its soleactive agent, or a composition that includes levodopa and one or moreother active agents such as carbidopa, benserazide, entacapone,tolcapone, selegiline and/or rasagiline. Contemplated methods oftreatment included those directed to diseases or disorders includingrestless leg syndrome, Parkinson's disease, secondary parkinsonism,Huntington's disease, Parkinson's like syndrome, progressivesupranculear palsy (PSP), multiple system atrophy (MSA), amyotrophiclateral sclerosis (ALS), Shy-Drager syndrome and conditions resultingfrom brain injury including carbon monoxide or manganese intoxication.In an embodiment, continuous administering may include transdermal,intradermal, subcutaneous, intravenous, or intraduodenal administration,e.g. may include the use of an infusion pump.

In one embodiment, a method of treating or ameliorating a neurologicalor movement disorder in a patient in need thereof is providedcomprising: administering a therapeutically effective amount of acomposition comprising a carbidopa basic amino acid salt (e.g.,carbidopa arginine) and administering a therapeutically effective amountof a composition comprising levodopa. For example, a compositioncomprising carbidopa and arginine may be administered substantiallycontinuously and/or the composition comprising levodopa may beadministered at discrete intervals (for example by oral administrationone, two, three or more times a day), during the substantiallycontinuous administration of composition comprising a carbidopa argininesalt.

Also provided herein is a method of substantially continuouslyinhibiting decarboxylase activity and/or a method of increasing thehalf-life of levodopa in a patient receiving levodopa, comprisingadministering (e.g. substantially continuously) to the patient a liquidor gel composition comprising a carbidopa salt such as carbidopaarginine. For example, the disclosed methods may result in a half-lifeof levodopa in the plasma of a patient that is at least 1.5, or at leasttwo times, longer after continuous administration of carbidopa ascompared to the half life of levodopa in a patient's serum afteradministering levodopa with discrete, oral administration of carbidopa.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-1C depict the mass spectra of carbidopa arginine salt.

FIGS. 2A-2C depicts the mass spectra of levodopa arginine salt.

FIGS. 3A-3C show the mean levels of carbidopa determined in plasma offemale Landrace × large white swine (30-35 kg) following oraladministration of (#A) Stalevo (100/25/200 mg, LD/CD/E), (3B)Dopicar+Lodosyn (125/25 mg LD/CD), (3C) Sinemet CR (100/25 mg, LD/CD) q8and 12 h, with (squares) or without (diamonds) continuous subcutaneousadministration of 3% carbidopa solution.

FIGS. 4A-4B shows brain levels of dopamine and L-Dopa (4A, left andright panels), and plasma levels of L-dopa and carbidopa (4B, left andright panels, respectively) determined in CD-1 mice following oraladministration of levodopa/carbidopa with or without continuoussubcutaneous administration of carbidopa.

FIGS. 5A-5B depicts mean level of L-Dopa (5A) and carbidopa (5B)determined in plasma of female Landrace × large white swine (30-35 kg)following continuous subcutaneous administration of 0, 2 and 4%carbidopa with oral administration of Sinemet® (100/25 mg) q8h.

FIGS. 6A-6B depict mean levels of dopa determined in plasma of twofemale Landrace × large white swine (30-35 kg) (6A, Pig #3; 6B, Pig #4)following continuous subcutaneous administration of 2 and 4% carbidopawith oral administration of Dopicar® (125/12.5 mg LD/CD)+Lodosyn® (12.5mg CD) q12h.

FIG. 7 shows the mean (±SD) LD (levodopa) concentrations (ng/ml) asdetermined in plasma of female Landrace × large white swine (30-35 kg)following oral administration of Stalevo (LD/CD/E100/25/200), q8h, withor without continuous subcutaneous benserazide or carbidopa (60 mg/day).

FIGS. 8A-8B depict plasma levels of (8A) L-dopa and (8B) 3-O-methyldopa(3-OMD) as determined in plasma of female Landrace × large white swine(30-35 kg) following continuous subcutaneous administration of 2%carbidopa, with or without 2.5% entacapone, and oral administration ofL-dopa/Carbidopa (LD/CD).

FIG. 9 shows the results of transdermal delivery of carbidopa propylester (CDPE).

FIGS. 10A-10B depict plasma levels of (10A) levodopa and (10B) carbidopaas determined in plasma of female Landrace × large white swine (30-35kg) following oral administration of enteric coated or uncoated LD andCD as arginine salts (designated LDs and CDs, respectively, 100/25 mgLD/CD) as compared to Sinemet (100/25 mg LD/CD).

FIG. 11 depicts the inhibition of L-dopa decarboxylation by carbidopaand carbidopa propyl ester.

FIGS. 12A-12B depict (12A) the inhibition of L-dopa decarboxylation andthe metabolism of L-dopa to dopamine (12B) by carbidopa and carbidopapropyl ester in liver extract.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein is a liquid composition having a physiologicallyacceptable pH that includes an arginine salt of carbidopa (e.g.,arginine and carbidopa) that is stable at room temperature, which canfacilitate continuous delivery of an effective amount carbidopa to apatient in a minimally invasive fashion (e.g. a disclosed liquidformulation comprises a significantly high concentration of carbidopa sothat administration of large amounts of liquid are not required) Suchformulations may facilitate continuous decarboxylase inhibition whichprolongs the half life of levodopa. For example, results from in vivostudies, as described below, in which L-dopa was administeredcontinuously in parallel with oral administration of carbidopa every 6-8hours demonstrate a pulsatile pattern of L-dopa plasma levels thatcoincide with carbidopa oral dosing regimen, but concomitant and/orfrequently repeated, e.g., simultaneous dosing of dopa decarboxylaseinhibitor (e.g. of carbidopa or a salt thereof, or benserazide) with orwithout COMT inhibitors with discrete or continuous administration oflevodopa is more effective in the treatment of e.g., Parkinson'sdisease. Further, it has been discovered that the pharmacokineticprofile of, for example, carbidopa (with or without entacapone) supportssuch new therapies that include substantially continuous administrationof dopa decarboxylase inhibitors (e.g. benserazide or carbidopa or asalt thereof) with or without COMT inhibitors together withadministration (continuous or at discrete intervals) of e.g. levodopa ora salt thereof.

Provided herein are formulations of carbidopa that unexpectedly allowfor stable dissolution of higher concentrations (e.g., greater than 1%by weight) of carbidopa and/or levodopa at e.g. physiologicallyacceptable pH, for e.g., substantially continuous subcutaneous ortransdermal administration. Such formulations may also be suitable forintravenous, intradermal, oral or intraduodenal administration. Forexample, provided herein are formulations and methods capable ofobtaining substantially constant inhibition of dopa decarboxylaseactivity upon administration, thereby increasing the half life ofadministered levodopa and substantially reducing the pulsatility oflevodopa plasma levels to avoid low trough levels of plasma levodopa.

A treatment strategy of continuous carbidopa administration inaccordance with the present invention may simulate L-dopa substantiallycontinuously. For example, therapies and/or methods of the presentinvention may extend a levodopa oral dosing regimen to about 2 to about3 times/day, and/or reduce daily dose of levodopa, and/or reduce or eveneliminate the risk of motor complications associated with standard orallevodopa formulations in Parkinson's patients.

Compositions

Provided herein, in an embodiment, is a pharmaceutically acceptableformulation that includes a carbidopa salt such as carbidopa arginine,that allows for substantially continuous administration of carbidopa.For example, while carbidopa free base is practically insoluble inalcohol, chloroform or ether and only slightly soluble in water,provided herein, for example, is a stable liquid formulation thatincludes carbidopa and may be suitable for substantially continuousadministration to a patient. Further, such formulations may have aphysiologically acceptable pH.

In one aspect, the present invention relates to a carbidopa salt with abasic amino acid selected from arginine, lysine, or histidine. In onepreferred embodiment, the salt is the carbidopa arginine salt.

The disclosure also provides, in an embodiment, a liquid formulationcomprising a disclosed carbidopa salt. For example, a disclosedcarbidopa salt (e.g. carbidopa arginine, carbidopa histidine, carbidopalysine) may be dissolved in an aqueous solution, (e.g., having a pH ofabout 6 to 9.5, preferably from about 7 to about 9, more preferably fromabout 8 to 9 at 25 C or at 30° C. Alternatively, carbidopa (free base)and a basic amino acid salt (e.g. arginine, histidine and/or lysine) aredissolved together in a liquid (e.g. an aqueous liquid) to form adisclosed liquid formulation. Disclosed liquid formulations may includeabout 1.0% by weight or more carbidopa or carbidopa salt, for example,may include about 1% to about 20% by weight or more carbidopa, e.g.,about 2% to about 10% by weight carbidopa. For example, a liquidformulation may include carbidopa and a basic amino acid (such asarginine) in molar ratio of about 1:0.5 to about 1:2.5, or about 1:1 toabout a 1:1.2, e.g., about 1:1 or 1:1.1.

Disclosed liquid formulations (e.g. a liquid composition comprisingcarbidopa and arginine or an arginine salt of carbidopa) may be stablefor 24 hours, for 48 hours, for 7 days, or more at 25° C. For example,an exemplary liquid formulation may include a 1:1.1 molar ratio ofcarbidopa:arginine, with about 2% to about 15%, or about 2% to about10%, or 2% to about 6% by weight carbidopa. Such a carbidopa:arginineliquid formulation may be more stable at 7 days as compared to a liquidcomposition that includes a lysine or histidine salt of carbidopa.

In some embodiments, disclosed liquid formulations or compositions areliquid solutions, i.e. are substantially homogenous liquid mixtures.Such liquid mixtures may comprise water and/or other excipients. Inanother embodiment, disclosed liquid compositions may be substantiallynon-aqueous.

For example, as disclosed in Example 6, below, a stable liquid solutioncan be unexpectedly formed from carbidopa and arginine. Such a solutionis stable at room temperature, e.g., is a substantially clear solution,even at high carbidopa concentrations of 2, 3, 4, 6, and/or 8 weightpercent carbidopa. Such solutions, e.g. up to about 6 weight percentcarbidopa, are stable (e.g., no precipitation) at least for 48 hours.Further, because such disclosed solutions, even at high concentrationsof carbidopa, have a physiologically acceptable pH, such solutions canbe adjusted to an appropriate pH, but still have a significant amount ofcarbidopa in a smaller volume so that it facilitates patientadministration, without e.g. administering large volumes of solution.

Further, solutions having carbidopa and arginine (e.g., the argininesalt of carbidopa) are unexpectedly more stable even as compared tosolutions of carbidopa with histidine or lysine, as shown below in e.g.Example 6.

Contemplated liquid formulations may, in some embodiments, furthercomprise levodopa or levodopa and arginine, and/or optionally acatechol-O-methyl transferase (COMT) inhibitor, such as entacapone ortolcapone; and/or a monoamine oxidase (MAO)-A or MAO-B inhibitor, suchas moclobemide, rasagiline, selegiline or safinamide.

Also disclosed herein is a levodopa salt with a basic amino acidselected from the group consisting of arginine, lysine, and histidine,for example, an arginine salt of levodopa. For example, provided hereinis a liquid formulation comprising an arginine salt of levodopa, or aliquid formulation comprising arginine and levodopa. In an embodiment,provided herein is a liquid formulation that includes levodopa andarginine in a molar ratio of about 1:1.5 to about 1:2.5, or about 1:1.8to about 1.20. Such levodopa and arginine formulations or solutions mayhave a pH of about 8 to about 10, for example, about 8.5 to about 9.5. Adisclosed formulation having levodopa and arginine may include about 2%,3%, 4%, 5%, 6% or more by weight levodopa, e.g., may include about 4% ormore by weight levodopa.

In some embodiments, a disclosed liquid formulation will be stable for aperiod of 1 day, 2 days, 3 days, 1 week, or 1 month or more at roomtemperature. In an embodiment of the invention, a disclosed liquidformulation further comprises a pharmaceutically acceptable excipientsuch as e.g., N-methylpyrrolidone (NMP), polyvinylpyrrolidone (PVP), orpropylene glycol, or a combination of one or more, and may furthercomprise one or more antioxidants such as, but not limited to, N-acetylcysteine, sodium bisulfite, gluthatione, and ascorbic acid. For example,in one embodiment, provided herein is a stable liquid formulation thatcomprises about 0.5 to about 20% of carbidopa (e.g. about 2% to about6%), about 1 to about 20% arginine, about 0 to about 30% NMP, about 0 toabout 5% PVP, and/or about 0 to about 5% of one or more water solubleantioxidants, by weight.

The invention further provides a stable lyophilized powder comprising adisclosed carbidopa salt e.g., arginine salt. In one embodiment, suchstable lyophilized powder may comprise about 20-99% of the carbidopasalt, about 0-60% NMP, about 0-15% PVP, and about 0-5% of one or morewater soluble anti oxidants. The lyophilized powder can be reconstitutedinto a liquid formulation by addition of water alone or water with NMP,and may include or not include antioxidants.

Liquid formulations of the invention may be designed for continuousadministration of a carbidopa or levodopa salt to a patient in needthereof. For example, a patient may be substantially continuouslyadministered (e.g. subcutaneously, transdermally, intraduodenally,intradermally, or intravenously) a formulation that includes a disclosedcarbidopa salt such as the arginine salt of carbidopa, while levodopa, alevodopa salt, or a composition comprising levodopa is orallyadministered at discrete intervals, e.g., 2, 3, 4, or 5 times a day.

As used herein in the specification, the term “a composition comprisinglevodopa” contemplates formulations that comprise levodopa, optionallytogether with a decarboxylase inhibitor, a catechol-O-methyl transferase(COMT) inhibitor, and/or a MAO-A or MAO-B inhibitor. For example, acomposition comprising levodopa includes a dosage formulation thatcomprises levodopa (or a salt thereof) and optionally another drug,where the dosage formulation may be an immediate release, controlledrelease, dual release or multiple release formulation suitable for oraladministration.

The term “decarboxylase inhibitor” refers to a dopa decarboxylaseinhibitor, e.g., a drug that inhibits the peripheral metabolism oflevodopa to dopamine by aromatic L-amino acid decarboxylase such ascarbidopa and benserazide.

The term “pharmaceutically acceptable carrier” or “pharmaceuticallyacceptable excipient” as used herein refers to any and all solvents,dispersion media, preservatives, antioxidants, coatings, isotonic andabsorption delaying agents, and the like, that are compatible withpharmaceutical administration. The use of such media and agents forpharmaceutically active substances is well known in the art. Thecompositions may also contain other active compounds providingsupplemental, additional, or enhanced therapeutic functions.

The term “physiologically acceptable pH” is understood to mean a pH ofe.g., a composition that facilitates administration of the compositionto a patient without significant adverse effects, e.g. a pH of about 4to about 9.

COMT inhibitors refer to inhibitors that inhibit the degradation oflevodopa to 3-methyldopa by catechol-O-methyl transferase and prolongthe action of levodopa, such as entacapone or tolcapone. For example,compositions comprising levodopa contemplated herein may also include adecarboxylase inhibitor (carbidopa or benserazide) and entacapone, e.g.“triple therapy”.

MAO-A or MAO-B inhibitors prevent the breakdown of dopamine by monoamineoxidases, e.g., moclobemide, rasagiline, selegiline or safinamide, morepreferably, rasagiline.

Also contemplated herein is a kit comprising: a) a first formulationcomprising a carbidopa:arginine and/or carbidopa and arginine, whereinsaid first formulation is suitable for continuous administration; b) asecond formulation comprising levodopa or an arginine salt of levodopa,wherein said second formulation is suitable for oral administration; andc) instructions for administration of formulation a) in conjunction withformulation b). The formulation a) comprising the carbidopa salt may besuitable for continuous administration by any suitable route such astransdermally, intravenously, subcutaneously, intradermally,intramuscularly or intraduodenally.

The first formulation of a contemplated kit comprising the carbidopasalt may be liquid or a lyophilized powder that can be reconstitutedinto a liquid formulation, or, for example, may form part of atransdermal patch, and may be designed for continuous administration byany suitable route such as, but not limited to, transdermally,intravenously, subcutaneously, intradermally, intramuscularly orintraduodenally. In an embodiment, the first formulation comprises adisclosed carbidopa salt and is suitable for administrationsubcutaneously. The second formulation of a contemplated kit may includethe levodopa, a levodopa ester, a levodopa salt, or a compositioncomprising levodopa, and may be presented as any suitable oral dosagesuch as, but not limited to, pills, tablets, dispersible tablets,capsules, liquid, and the like. In an embodiment, the second formulationmay be in the form of an immediate release, controlled release or dualrelease oral formulation that comprises both levodopa and benserazide,or both levodopa and carbidopa. Such oral formulation in the form ofpills, tablets, or the like, may comprise a ratio of carbidopa orbenserazide to levodopa of about 1:10 to 1:4, preferably from about 1:4to 1:1. Other contemplated second formulations include formulations,e.g., tablets that include levodopa, carbidopa, and entacapone, or e.g.a tablet that includes levodopa arginine salt and/or carbidopa argininesalt.

In another embodiment, the kit comprises a first liquid formulationcomprising carbidopa and arginine suitable for, but not limited to,transdermal, intravenous, subcutaneous, intradermal, intramuscular,intraduodenal continuous administration, and a second formulation in theform of an immediate release, controlled release or dual release oralformulation comprising levodopa and carbidopa. The oral formulation inthe form of pills, tablets, or the like, may comprise a ratio ofcarbidopa to levodopa from about 1:10 to about 1:4, preferably fromabout 1:4 to about 1:1.

In another aspect, the present invention relates to a formulationcomprising a carbidopa ester such as, but not limited to, the ethyl,propyl, isopropyl or hexyl ester of carbidopa, and salts thereof.Examples of levodopa esters contemplated herein include the alkylesters, e.g., the methyl, ethyl, propyl, or isopropyl ester, or thebenzyl ester.

Methods

In a further aspect, the present invention provides a method fortreatment of a disease or disorder characterized by reduced and/orfluctuating levels of dopamine in a patient's brain, comprisingco-administering substantially continuously to a patient in need atherapeutically effective amount of a decarboxylase inhibitor, a salt oran ester thereof, together with a therapeutically effective amount oflevodopa or salt thereof or a composition comprising levodopa. As shownin the Examples, separate continuous administration of carbidopa,together with administration of levodopa, even with discrete (e.g. oral)administration of levodopa, to a patient results in significantly higherlevels of levodopa in the plasma of a patient upon administration ascompared to a current standard of discrete carbidopa and levodopasimultaneous dosing. For example, disclosed methods may result in ahalf-life of levodopa in the plasma of a patient that is at least 1.5,or at least two times, longer after continuous administration ofcarbidopa as compared to the half life of levodopa in a patient's serumafter administering levodopa without continuous administration ofcarbidopa (e.g., with discrete, oral administration).

Contemplated administration of e.g., carbidopa and levodopa, followingthe disclosed methods, typically can be carried out over a defined timeperiod (usually weeks, months or years depending upon the combinationselected). Contemplated therapies are intended to embrace administrationof multiple therapeutic agents in a manner wherein a dopa decarboxylaseinhibitor is administered substantially continuously while levodopa isadministered at discrete intervals, as well as administration ofcontemplated therapeutic agents, or at least two of the therapeuticagents, in a substantially simultaneous manner. Administration can beeffected by any appropriate route including, but not limited to, oralroutes, intravenous routes, intramuscular routes, intradermal routes,subcutaneously, transdermally, and direct absorption through mucousmembrane tissues.

In some embodiments, levodopa can be administered by the same route orby different routes as compared to administration of e.g. a contemplatedcarbidopa formulation. For example, carbidopa may be administeredsubcutaneously, e.g., substantially continuously, while levodopa may beadministered orally, e.g. at discrete intervals. In an embodiment, adisclosed liquid carbidopa composition (e.g. having carbidopa andarginine) is administered substantially continuously, while an oralcomposition that includes levodopa (and may also include one or moreother active agents such as a dopa decarboxylase inhibitor) isadministered at discrete intervals. Alternatively, for example, bothlevodopa and carbidopa may be administered subcutaneously ortransdermally.

The disease or disorder characterized by reduced levels of dopamine inthe brain contemplated herein are neurological or movement disordersincluding restless leg syndrome, Parkinson's disease, secondaryparkinsonism, Huntington's disease, Shy-Drager syndrome and conditionsresulting from brain injury including carbon monoxide or manganeseintoxication. In one preferred embodiment, the disease to be treated isParkinson's disease.

In preferred embodiments, the contemplated decarboxylase inhibitor isthe arginine salt of carbidopa. A disclosed carbidopa/arginineformulation may be administered substantially continuously using e.g. aliquid formulation, for example, via a pump for subcutaneous infusion(insulin pump) at an average rate of about 10-250 μl/hour, preferablyabout 15-85 μl/hour, in conjunction with oral administration oflevodopa, an arginine salt of levodopa, or composition comprisinglevodopa.

For example, a method for treating a neurological or movement disordere.g., Parkinson's disease, is provided herein comprising substantiallycontinuously administering to a patient in need thereof apharmaceutically effective amount of a composition comprising acarbidopa and an amino acid such as arginine, lysine or histidine, andadministering a pharmaceutically effect amount of composition comprisinglevodopa. For example, the composition comprising a carbidopa andarginine may be liquid at room temperature. The disclosed compositionmay be administered substantially continuously over 12 hours, 1 day, 1week, or more. The composition comprising levodopa may form all or partof an immediate release, controlled release, or dual release oralformulation comprising levodopa and optionally benserazide or carbidopa,and may be administered 1, 2, 3, or 4 times a day, or more for example,by oral administration (e.g. by tablet).

Also provided herein is a method for treatment of a disease or disordercharacterized by reduced levels of dopamine in a patient's brain, (e.g.,Parkinson's disease) comprising co-administering substantiallycontinuously to a patient in need a therapeutically effective amount ofa disclosed levodopa salt.

The invention now being generally described, it will be more readilyunderstood by reference to the following examples which are includedmerely for purposes of illustration of certain aspects and embodimentsof the present invention, and are not intended to limit the invention inany way.

EXAMPLES Example 1 Preparation and Characterization ofCarbidopa-Arginine Salt

Carbidopa-Arginine salt was prepared as follows:

Carbidopa (CD) [Teva Pharmaceuticals Ltd., Israel] was weighed in asuitable container with L-arginine [Merck] (at molar ratio of 1:1) and a0.2% sodium bisulfite [Sigma] solution in water was added to obtain afinal concentration of 4.0% carbidopa. The mixture was heated to 65±10°C. with constant stirring. When the solids were completely dissolved,solution was filtered using 0.45 μM nylon membrane. The filteredsolution was immediately frozen in dry ice and subsequently subjected tolyophilyzation. Off-white crystals were obtained and subsequentlysubjected to MS analysis. The MS analytical results clearly showedcarbidopa and L-arginine ions and fragments (FIG. 1 a). Peak 249represents carbidopa+Na (226+23) with fragments: 227, 188 & 144 (FIG. 1b); Peak 176 represents arginine+2H (174+2) with fragments: 157,130 &116 (FIG. 1 c).

Example 2 Preparation of Carbidopa Solution/Formulation for SubcutaneousAdministration

A 4% Carbidopa solution/formulation was prepared as follows:

Carbidopa [Assia Ltd., Israel] was weighed in a suitable container andwater was then added to obtain 73% of the total projected batch weight.Mixture was stirred at room temperature for 20 minutes. L-Arginine[Sigma] was added to the mixture to obtain a molar ratio 1:1 withcarbidopa. The mixture was heated to 65±10° C. with constant stirring.When the solids were completely dissolved, N-methyl 2-pyrrolidone[Pharmasolve, ISP] was added to obtain the final concentration of 10%(w/w). Sodium bisulfite [Sigma] solution was prepared and added toobtain a final concentration of 1% (v/w). Stirring was continued foradditional 30 minutes at 65±3° C. Thereafter, PVP [Polyvinylpyrrolidone,Sigma] solution was prepared and added to obtain a final concentrationof 1% (v/w). Stirring was continued for 30 minutes at 65±3° C. Heatingwas stopped and the preparation was allowed to cool down to roomtemperature. Solution was filtered using a sterile 0.22 μM PVDFmembrane.

Carbidopa-Arginine solutions/formulations, 2 and 3%, were prepared bydiluting the 4% carbidopa-arginine solution/formulation with therespective amount of double distilled water (DDW).

Example 3 Preparation of Carbidopa Solution/Formulation for SubcutaneousAdministration

A 6% Carbidopa solution/formulation was prepared as follows:

Carbidopa [Teva] and L-arginine [Merck] (molar ratio 1:1.1) were weighedin a suitable container and water was then added to obtain 84% of thetotal projected batch weight. N-methyl 2-pyrrolidone [Pharmasolve, ISP]was added to obtain the final concentration of 5% (w/w) Sodium bisulfite[Sigma] solution was prepared and added to obtain a final concentrationof 0.1% (v/w). The mixture was heated to 65±10° C. with constantstirring. When the solids were completely dissolved heating was stoppedand the preparation was allowed to cool down to room temperature.Solution was filtered using a sterile 0.22 μM PVDF membrane.

Example 4 Preparation of Carbidopa Solution/Formulation for SubcutaneousAdministration

A 4% carbidopa solution/formulation was prepared as follows:

Carbidopa [Teva] and L-arginine [Merck] (molar ratio 1:1.1) were weighedin a suitable container and water was added to obtain 89% of the totalprojected batch weight. N-methyl 2-pyrrolidone [Pharmasolve, ISP] wasadded to obtain the final concentration of 3.5% (w/w). Sodium bisulfite[Sigma] solution was prepared and added to obtain a final concentrationof 0.05% (v/w). The mixture was heated to 65±10° C. with constantstirring. When the solids were completely dissolved, heating was stoppedand the preparation was allowed to cool down to room temperature. Thesolution was filtered using a sterile 0.22 μM PVDF membrane.

Carbidopa-Arginine solutions/formulations, 2 and 3%, were prepared bydiluting the 4% Carbidopa-arginine solution/formulation with therespective amount of double distilled water (DDW) containing 3.5% N-MP,with or without 0.05% sodium bisulfite.

Example 5 Preparation of Carbidopa Formulation for Transdermal Delivery

An 8% Carbidopa formulation was prepared as follows:

Carbidopa [Teva] and L-arginine [Merck] (molar ratio 1:1) were weighedin a suitable container and propylene glycol [Merck] was added to obtain75% of the total projected batch weight. Sodium bisulfite [Sigma]solution was prepared and added to obtain a final concentration of0.05%. The mixture was heated to 65±10° C. with constant stirring. Whenthe solids were completely dissolved, heating was stopped and thepreparation was allowed to cool down to room temperature. PEG-400[Merck], 10% of the total projected batch weight, was added. The pH wasadjusted to 7.5 with 85% lactic acid [Fluka].

Example 6 Preparation and Stability of Carbidopa-ArginineCarbidopa-Lysine and Carbidopa-Histidine Solutions/Formulations

Carbidopa solutions/formulations were prepared as follows:

Carbidopa [Teva] was weighed in a suitable container with L-arginine[Merck] or L-lysine [Sigma] or L-histidine [Sigma] (at molar ratio of1:1, 1:1.1 or 1:2) and water was added. N-methyl 2-pyrrolidone[Pharmasolve, ISP] was added to obtain the final concentration of 5%(w/w). Sodium bisulfite [Sigma] solution was prepared and added toobtain a final concentration of 0.05% (v/w). The mixture was heated to68±3° C. with constant stirring. When the solids were completelydissolved, heating was stopped and the preparation was allowed to cooldown to room temperature. Stable formulations (2% CD:Lysine and 2%CD:Arginine 1:1.1 molar ratio) were further subjected to HPLC analysisat t=0 and t=7 days at 25° C.

The results show the significant difference between the three basicamino acids [L-Arginine (PI-10.76), L-Lysine (PI-9.74) and histidine(PI-7.59)] with respect to their effect on the solubility and stabilityof carbidopa in aqueous solution: Table 1 indicates the solubility andstability of carbidopa in these aqueous solutions with basic amino acids(arginine, lysine or histidine) as determined visually (Table 1A) or byUV HPLC (Table 1B). With arginine, a stable solution of 6% carbidopa wasprepared, whereas a solution with only less than 4% could be formulatedwith lysine (Table 1A). Furthermore, a solution of 2% carbidopa withlysine was less stable than with arginine after 7 days at 25° C. (Table1B). In addition, a stable solution with histidine at concentrations ≧1%could not be made (Table 1A).

TABLE 1A Carbidopa and Arginine Solution CD Concentration (%) 2 4 4 5 68 Molar Ratio 1 to 1 1 to 1 1 to 1.1 1 to 1.1 1 to 1.1 1 to 1.1CD:Arginine pH of the Solution 8.2 8.2 8.4 8.5 8.7 8.9 SolutionAppearance Clear, Clear, Clear, Clear, Clear, Clear, slightly slightlyslightly slightly slightly slightly yellow yellow yellow yellow yellowyellow Stability after Stable Stable Stable Stable Stable Precipitated48 h (visual) within 24 h Carbidopa and lysine solutions CDConcentration (%) 2 4 2 4 Molar Ratio 1 to 1 1 to 1 1 to 1.1 1 to 1.1CD:Lysine PH of the Solution 8.1 N/A 8.2 8.23 Solution Appearance Clear,Didn't Clear, Precipitated slightly dissolve yellow within few yellowminutes Stability after Precipitated N/A Stable N/A 48 h (visual) after2 h Carbidopa and histidine solutions CD Concentration (%) 1 4 2 4 MolarRatio 1 to 1.1 1 to 1.1 1 to 2 1 to 2 CD:Histidine pH of the SolutionN/A N/A 6.7 N/A Solution Appearance Didn't Didn't Clear, Didn't dissolvedissolve white dissolve Stability after N/A N/A Precipitated N/A 48 h(visual) after 1 h

TABLE 1B Amino Molar CD Impurities Profile (Area %) Acid Ratio CD Timeof Assay RT RT RT RT (AA) CD:AA (%) Analysis (%) 3-OMD 5.3 12.6 13.614.5 Lysine 1:1.1 2 t = 0 95.1 0 3.3 0 0.50 1.07 Arginine 1:1.1 2 t = 094.1 0 4.5 0 0.41 1.05 Lysine 1:1.1 2 t = 7 d 70.8 0 N/A 0 1.39 26.4 atRT Arginine 1:1.1 2 t = 7 d 77.6 0 N/A 0 1.34 19.4 at RT N/A = NotApplicable

Example 7 Preparation of Levodopa-Arginine Salt

Levodopa-Arginine salt was prepared as follows:

Levodopa (LD) [Teva] was weighed in a suitable container with L-arginine[Merck] (at molar ratio of 1:1.8) and a 0.2% sodium bislfite [Sigma]solution in water was added to obtain a final concentration of 4.4%L-Dopa. The mixture was heated to 65±10° C. with constant stirring. Whenthe solids were completely dissolved, solution was filtered using 0.45μM nylon membrane. The filtered solution was immediately frozen in dryice and subsequently subjected to lyophilization. The filtered solutionwas immediately frozen in dry ice and subsequently subjected tolyophilyzation. Off-white crystals were obtained and subsequentlysubjected to MS analysis. The MS analytical results (shown in FIG. 2)clearly showed LD and Arginine ions. LD: 197 with fragments 178.97,151.96, 136.98 (FIGS. 2 a & 2 b); Arginine: 175 with fragments 130, 116(FIGS. 2 a & 2 c)

Example 8 Preparation of Carbidopa and Carbidopa/EntacaponeSolutions/Formulations for Subcutaneous Administration, and Their LocalSafety Evaluation in Pigs

A 10% carbidopa and 4/6% carbidopa/entacapone solutions/formulationswere prepared as follows:

Carbidopa [Assia Ltd.] was weighed in a suitable container and water wasthen added to obtain 73% of the total projected batch weight. Mixturewas stirred at room temperature for 20 minutes. L-Arginine [Sigma] wasadded to the mixture to obtain a molar ratio 1:1 with Carbidopa. Themixture was heated to 65±10° C. with constant stirring. When the solidswere completely dissolved, N-methyl 2-pyrrolidone [Pharmasolve, ISP] wasadded to obtain the final concentration of 10% (w/w). Sodium bisulfate[Sigma] solution was prepared and added to obtain a final concentrationof 1% (v/w). Stirring was continued for additional 30 minutes at 65±3°C. Thereafter, PVP [Polyvinylpyrrolidone, Sigma] solution was preparedand added to obtain a final concentration of 1% (v/w). Stirring wascontinued for 30 minutes at 65±3° C. Heating was stopped and thepreparation was allowed to cool down to room temperature. Solution wasfiltered using a sterile 0.22 μM PVDF membrane. The filtered solutionwas immediately frozen in dry ice and subsequently subjected tolyophilization. Lyophilized crystals were re-constituted with doubledistilled water to obtain 4 and 10% carbidopa solutions. Entacapone[extracted from Comtan®, Novartis] was added to the 4% carbidopasolution to obtain a final concentration of 6% (w/v). Both formulations(10% CD and 4/6% CD/E) were continuously administered sc to pigs for aperiod of 21 h to evaluate potential local reactions. Macroscopic andmicroscopic evaluations indicated that 21 h continuous subcutaneousadministration of these carbidopa solutions/formulations was safe.(Table 2).

Table 2 indicates the results of a histological evaluation of skinbiopsies obtained from female Landrace × large white swine followingcontinuous subcutaneous administration of 10% CD (carbidopa) or 4/6%CD/entacapone for a period of 21 h, at a rate of 25 or 82 μl/h.

TABLE 2 Pig #1 Pig #2 L R L R CD 10% CD/Ent 4/6% CD/Ent 4/6% CD 10%Infusion Rate Pod Activation (h) 25 μl/hr 21 h — 21 h — 82 μl/hr — 21 h— 21 h Parameter Histological Observation (Time post patch removal) 0 10d 0 10 d 0 10 d 0 10 d Lesion Subcutis No No No No No Subcutis NoLocalization Lesions Lesions Lesions Lesions Lesions LesionsDistribution Peri- Peri- vascular vascular Inflammation 0-1 0-1 GradePredominant N N Cell Type Necrosis — — Fibrosis — — Key: Localization:Epidermis, dermis, subcutis; _Distribution: Diffuse, multifocal,perivascular; Inflammation Scoring Grade: 0-no inflammation, 1-verymild, 2-moderate, 3-severe; Predominant Cell Type: lymphocytes (L),macrophages (M), neutrophils (N); Necrosis: Yes/No; Fibrosis: Yes/No

Example 9 The Effect of Continuous Subcutaneous Carbidopa Administrationon the Pharmacokinetic Profile of Levodopa and Carbidopa in Pigs

In this experiment, the purpose was to determine the effect ofcontinuous subcutaneous administration of carbidopa, withco-administration of oral L-dopa/carbidopa, on the pharmacokinetics oflevodopa in pigs. Pigs weighing 30-35 kg were administered orally witheither Stalevo® (Novartis, 100/25/200 mg, LD/CD/E), Dopicar®[Teva]+Lodosyn® (Merck & Co) (125/25 mg, LD/CD) or Sinemet CR® (MSD,100/25 mg, LD/CD) thrice or twice daily (q8 or 12 h, respectively) withor without carbidopa (60 mg/pig/d) for a total period of 68 h. Bloodsamples were collected at pre-determined time points and plasma levelsof L-dopa and carbidopa were analyzed by LC-MS.

Results showed that the co-administration of continuous subcutaneouscarbidopa with any oral LD preparation significantly increases (morethan ×2) the half live (VA) and AUC of levodopa. In contrast, increasedcarbidopa oral dose or frequency did not considerably improve the PKprofile of levodopa, as shown in Table 3. Also, constant, steady-state,levels of CD was maintained at 164±34 ng/ml during the 68 hours ofcontinuous SC administration of carbidopa (60 mg/pig/day). This was inopposition to the fluctuating pattern and very low trough levels of CDobtained after administration of standard treatment (FIG. 3). No signsof treatment related local or systemic toxicity were observed throughoutthe entire 68 h study period.

The pharmacokinetic parameters of levodopa determined in plasma offemale Landrace × large white swine (30-35 kg) following oraladministration of (A) Stalevo (100/25/200 mg, LD/CD/E), (B)Dopicar+Lodosyn (125/25 mg LD/CD), (C) Sinemet CR (100/25 mg, LD/CD) q8and 12 h (q8h=every 8 hours), with or without continuous subcutaneous(SC) administration of 3% carbidopa (CD) solution, with results depictsin Table 3:

TABLE 3A Oral Treatment Stalevo (100/25/200 mg) PK Parameters SCTreatment C_(max) T_(max) T_(1/2) AUC₀₋₈ AUC_(0-∞) Without SC CD 2392 ±1363.9 2.3 ± 0.89 1.4 ± 0.30  8109 ± 4145.2  8309 ± 4265.2 (n = 8) WithSC CD 2355 ± 1157.1 2.1 ± 1.00 2.9 ± 0.41 17527 ± 8470.8 19330 ± 8284.8(n = 12) Significance* (p) NS NS 2E−08 0.005 0.001

TABLE 3B Oral Treatment LD/CD (125/25 mg) PK Parameters SC TreatmentC_(max) T_(max) T_(1/2) AUC₀₋₈ AUC_(0-∞) Without SC CD 2472 ± 735.6  0.9± 0.53 1.1 ± 0.22  7200 ± 3093.2  7302 ± 3071.3 (n = 7) With SC CD 4050± 1369.5 0.8 ± 0.43 2.5 ± 0.43 17922 ± 4375.7 19230 ± 4625.5 (n = 14)Significance* (p) 0.005 NS 1E−07 7.4E−06 3.3E−06

TABLE 3C Oral Treatment Sinemet CR (100/25 mg) PK Parameters SCTreatment C_(max) T_(max) T_(1/2) AUC₀₋₈ AUC_(0-∞) Without SC CD 1691 ±556.2 0.9 ± 0.52 1.2 ± 0.19  4792 ± 1190.8  4929 ± 1196.6 (n = 8) WithSC CD 2830 ± 929.2 1.2 ± 0.92 2.6 ± 0.46 12688 ± 3516.3 13505 ± 3344.4(n = 15) Significance* (p) 0.002 NS 3.2E−08 2.3E−06 3.6E−07 *Using onetailed distribution equal variance T-Test

Example 10 The Effect of Continuous Subcutaneous Administration ofCarbidopa on Brain Distribution of Levodopa and Dopamine in Mice

In this experiment, the purpose was to determine the effect ofcontinuous subcutaneous administration of carbidopa (15 mg/kg/d) on thelevels of levodopa and dopamine in the brain following oraladministration of levodopa/carbidopa (32/8 mg/kg TID) in mice.

Mice were implanted subcutaneously with Alzet pumps containing Saline(Negative Control), Vehicle or Carbidopa solution. A day followingimplantation LD/CD was administered orally q8h. The level of levodopaand dopamine in the brain was determined following the 4^(th) oral doseof LD/CD. The results showed dopamine levels seven hourspost-administration of oral LD to be significantly higher in the brainsof mice continuously administered SC with carbidopa (FIG. 4A),concurrently with higher levels of plasma LD (FIG. 4B).

Example 11 Dose Effect of Continuous Subcutaneous CarbidopaAdministration on Local Toxicity and Pharmacokinetic Profile of Levodopaand Carbidopa in Pigs

In this experiment, the purpose was to determine the dose effect ofcarbidopa continuously administered subcutaneously to pigs on localtolerance and the pharmacokinetics of L-dopa.

Pigs weighing 30-35 kg were administered orally with Sinemet® (Merck &Co., 100/25 mg, LD/CD,), thrice daily (q8h), or Dopicar® (Teva)+Lodosyn®(Merck & Co., (125/25 mg LD/CD), twice daily (q12h), with continuoussubcutaneous vehicle, 2% or 4% carbidopa (0, 40 or 80 mg/pig/d,respectively) for a total period of 24 h. Blood samples were collectedat pre-determined time points and plasma levels of L-dopa and carbidopawere analyzed by LC-MS. Skin biopsies were collected from the infusionsites immediately, 1 and 2 weeks post-administration and local tolerancewas evaluated by histological analysis of H&E stained slides. Nohistological treatment-related abnormalities were observed at the sitesof infusion.

No significant dose effect on the plasma levels of L-dopa was observedwhen 2 or 4% carbidopa solutions were co-administered with Sinemet®(FIG. 5) or Dopicar®+Lodosyn® (FIG. 6). Thus, under the experimentalconditions employed, it was suggested that continuous subcutaneousadministration of 2% carbidopa, or less, may be sufficient to maintainoptimal inhibition of DDC (dopa decarboxylase) in pigs.

Example 12 The Effect of Continuous Subcutaneous Administration ofCarbidopa, with and without Continuous Subcutaneous Administration ofEntacapone, on the Pharmacokinetics of Levodopa in Pigs

In this experiment, the purpose was to determine the plasma levels ofL-dopa, following continuous subcutaneous administration of carbidopa,with or without entacapone, concomitantly with oral administration ofL-dopa/carbidopa in pigs. Plasma levels of L-dopa were measured byHPLC-ECD. The results in FIG. 8 show that entacapone effectively reducedthe levels of 3-OMD (3-ortho-methyldopa) (8B), but it did not furtherextend the pharmacokinetics of levodopa (8A), suggesting that entacaponeand/or COMT inhibition interferes with carbidopa/DDC-dependent, orother, LD metabolic pathways.

Example 13 The Effect of Continuous Subcutaneous Administration ofBenserazide on the Pharmacokinetics of Levodopa in Pigs

In this experiment, the purpose was to determine the plasma levels ofL-dopa, following co-administration of oral L-dopa/Carbidopa withcontinuous subcutaneous administration of another DDC inhibitor,benserazide. Plasma levels of L-dopa were measured by HPLC-ECD.

The results showed that benserazide extended the pharmacokinetic profileof LD, suggesting that continuous dopa-decarboxylase (DDC) inhibition,by any DDC inhibitor, increases the elimination half life of LD, asshown in FIG. 7.

Example 14 The Transdermal Delivery of Carbidopa Propyl Ester (CDPE)Through Full Thickness Pig Skin Ex Vivo using the Franz Cell DeliverySystem

In this experiment, the purpose was to determine the transdermaldelivery of carbidopa propyl ester through a full thickness porcineskin, ex vivo using the Franz cell delivery system. Gel formulationscontaining CDPE were prepared. Samples were collected from the receivercell at time 0, 16, 19 and 22 hours after formulation application on tothe skin. The amount of CD compounds in the receiver cell fluid wasdetermined by a spectrophotometer at 280 nM. The results shown in FIG. 9demonstrate that CDPE penetrates the skin in an enhancer-dose dependentmanner.

Example 15 The Effect of Oral Administration of Levodopa Arginine andCarbidopa Arginine Salts on the Pharmacokinetic Profile of Levodopa andCarbidopa

In this experiment, the purpose was to determine the pharmacokinetics ofLD and CD administered orally as arginine salts, either enteric-coatedor not. Pigs were orally administered with 255/45 mg LD-arginine salt(LDs)/CD-arginine salt (CDs) to 30-35 kg pigs in gelatin coated ornon-coated capsules (corresponding to 100/25 LD/CD). Plasma levels of LDand CD were measured by HPLC-ECD.

The results showed that LDs and CDs were absorbed more rapidly andefficiently as compared to LD/CD (Sinemet®), and that oraladministration of enteric coated LDs/CDs extended the PK of plasma LD(FIG. 10A) and CD (FIG. 10B).

Example 16 The Inhibitory Effect of Carbidopa Esters on the Activity ofDopa-Decarboxylases (DDC) In Vitro

In this experiment, the purpose was to determine the inhibitory effectof carbidopa esters (CDEs) on the activity of dopa-decarboxylases. DDCenzymes were obtained from porcine liver homogenate and their activitywas measured by comparing LD concentrations with and without carbidopapropyl ester (CDPE). Liver homogenate preparation was based on themethod described by Umezawa et al; (J. Antib. 1975, 28(12):947-52).

All samples were separated on high pressure liquid chromatographycolumns and the identity and concentration of L-dopa and dopamine weredetermined by HP UV-HPLC analysis at 280 nM.

The results shown in FIGS. 11 and 12 demonstrate that CDPE inhibits thedecarboxylation of L-dopa to dopamine, in a similar manner to carbidopaand benserazide.

EQUIVALENTS

While specific embodiments of the subject invention have been discussed,the above specification is illustrative and not restrictive. Manyvariations of the invention will become apparent to those skilled in theart upon review of this specification. The full scope of the inventionshould be determined by reference to the claims, along with their fullscope of equivalents, and the specification, along with such variations.

Unless otherwise indicated, all numbers expressing quantities ofingredients, reaction conditions, and so forth used in the specificationand claims are to be understood as being modified in all instances bythe term “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in this specification and attached claimsare approximations that may vary depending upon the desired propertiessought to be obtained by the present invention.

INCORPORATION BY REFERENCE

The entire contents of all patents, published patent applications,websites, and other references cited herein are hereby expresslyincorporated herein in their entireties by reference.

1. A pharmaceutically acceptable liquid composition comprising carbidopaand arginine, wherein the pH of the liquid composition is about 7 toabout 9 at 25° C.
 2. The pharmaceutically acceptable liquid compositionof claim 1, comprising at least about 2% by weight carbidopa.
 3. Thepharmaceutically acceptable liquid composition of claim 3, comprising atleast about 4% by weight carbidopa.
 4. The pharmaceutically acceptableliquid composition of claim 1, wherein the liquid composition issubstantially stable at 25° C. for 48 hours or more.
 5. Thepharmaceutically acceptable liquid composition of claim 4, wherein thecarbidopa and the arginine have a molar ratio of about 1:0.5 to about1:2.5.
 6. The pharmaceutically acceptable liquid composition of claim 5,wherein the carbidopa and the arginine have a molar ratio of about 1:1to about 1:1.2.
 7. The pharmaceutically acceptable liquid composition ofclaim 5, wherein the pH is about 8 to about
 9. 8. The pharmaceuticallyacceptable liquid composition of claim 4, further comprising apharmaceutically acceptable excipient.
 9. The pharmaceuticallyacceptable liquid composition of claim 8, wherein the pharmaceuticallyacceptable excipient is selected from the group consisting of:N-methylpyrrolidone, polyvinylpyrrolidone, propylene glycol, orcombinations thereof.
 10. The pharmaceutically acceptable liquidcomposition of claim 1, wherein the liquid composition is a liquidsolution further comprising water.
 11. The pharmaceutically acceptableliquid composition of claim 1, further comprising entacapone ortolcapone.
 12. The arginine salt of carbidopa.
 13. A liquid compositioncomprising the arginine salt of claim
 12. 14. A method of treatingParkinson's disease, comprising: orally administering, to a patient inneed thereof, a levodopa composition comprising a therapeuticallyeffective amount of levopoda or a pharmaceutically acceptable saltthereof, and administering substantially continuously to the patient thepharmaceutically acceptable liquid composition of claim
 1. 15. Themethod of claim 14, wherein continuously administering comprisestransdermal or subcutaneous administration.
 16. The method of claim 15,wherein continuously administering comprises the use of an infusionpump.
 17. The method of claim 14, wherein the levodopa compositionfurther comprises carbidopa, entacapone, or both.